An Efficacy and Safety Study of Palovarotene for the Treatment of Fibrodysplasia Ossificans Progressiva.

Key Inclusion Criteria: * Written, signed, and dated informed subject/parent consent; and for subjects who are minors, age-appropriate assent (performed according to local regulations). * Males or females at least 4 years of age. * No flare-up symptoms within the past 4 weeks, including at the time of enrollment. * Abstinent or using two highly effective forms of birth control. * Accessible for treatment and follow-up; able to undergo all study procedures including low-dose WBCT (excluding head) without sedation. Key Exclusion Criteria: * Weight \<10 kg. * Concomitant medications that are strong inhibitors or inducers of cytochrome P450 (CYP450) 3A4 activity; or kinase inhibitors such as imatinib. * Amylase or lipase \>2x above the upper limit of normal (ULN) or with a history of chronic pancreatitis. * Elevated aspartate aminotransferase or alanine aminotransferase \>2.5x ULN. * Fasting triglycerides \>400 mg/dL with or without therapy. * Female subjects who are breastfeeding. * Subjects with uncontrolled cardiovascular, hepatic, pulmonary, gastrointestinal, endocrine, metabolic, ophthalmologic, immunologic, psychiatric, or other significant disease. * Simultaneous participation in another clinical research study (other than palovarotene studies) within 4 weeks prior to Screening; or within five half-lives of the investigational agent, whichever is longer. * Any reason that, in the opinion of the Investigator, would lead to the inability of the subject and/or family to co…